A radio access network (RAN) typically includes base transceiver stations (BTSs), each of which radiate to define one or more wireless coverage areas. When a wireless communication device (WCD) attempts to establish an outgoing voice or data call via the RAN, the WCD may transmit one or more access probe messages to at least one BTS in range of or nearby the WCD. One of the purposes for doing so is to contact a BTS that can provide, via one of its defined wireless coverage areas, one or more wireless traffic channels to facilitate the call.
Typically, the WCD transmits a sequence of access probe messages to a first BTS via a first wireless coverage area defined by the first BTS. If the WCD receives a response to one of these access probe messages from the first BTS, the WCD may establish the call via the first wireless coverage area and proceed to use the first wireless coverage area to send and receive bearer data. However, if the WCD does not receive a response from the first BTS, the WCD may transmit another sequence of access probe messages to a second BTS via a second wireless coverage area defined by the second BTS.
If the WCD receives a response to one of the second sequence of access probe messages from the second BTS, the WCD may establish the call via the second wireless coverage area and proceed to use the second wireless coverage area to send and receive bearer data. However, if the WCD does not receive a response from the second BTS, the WCD may transmit another sequence of access probe messages to a third BTS via a third wireless coverage area defined by the third BTS. This process continues in a similar fashion until either the WCD receives a response from a BTS or the WCD gives up attempting to establish the call.